大连市厘米级精度的似大地水准面精化     

尹水清王虎  王贵明 《东北测绘》2008,31(1):165-167

论述了大地水准面精化的方法、原理以及大连市似大地水准面的确定。  相似文献   

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韩建成  申文斌 《大地测量与地球动力学》2007,27(5):38-43

???????????????1???1??(10 ^-5 ms ^-2 ??)??????????????????????????????????????????????,????????????????????????1???1??????????????????????????????÷??????????衣 ????????????????????????????????????÷??????1???1???????????????????????????  相似文献   

水体对精化局部似大地水准面的影响     

蒋勇  施昆  黄瑞金 《四川测绘》2009,32(4):171-174

在精化局部似大地水准面时，由于对大地水准面精度的要求不高或者精化区域的水下地形数据缺乏等因素，往往很少考虑湖泊水体对局部似大地水准面的影响。本文将通过分析水体对局部地形改正和地形均衡改正的影响，然后通过实例计算得出了湖泊水体对精化局部似大地水准面的影响。  相似文献   

Semi-analytical solution for viscous Stokes flow in two eccentrically nested spheres     

Nicola Tosi  Zden&#;k Martinec 《Geophysical Journal International》2007,170(3):1015-1030

Applying the infinite Prandtl number approximation, a semi-analytical solution for computing 2-D axisymmetric viscous Stokes flow in a model consisting of two eccentrically nested spheres of different viscosities is derived. Since numerical codes based on spectral or finite techniques for modelling mantle flow in a spherical geometry in the presence of lateral viscosity variation are becoming more and more popular, reliable examples for testing and validating such codes are extremely useful. The eccentrically nested sphere solution was used to test a numerical algorithm based on a mixed spherical-harmonic finite-element formulation of the Stokes problem, and good agreement was obtained.  相似文献   

CQG2000似大地水准面模型 在青藏高原地区区域重力调查中的应用     

邸志众  周纪平 《物探与化探》2007,31(5):451-454

区域重力调查中,GPS高程测量的精度直接影响重力测量成果的精度.用国内最新研制的测绘科技成果--CQG2000似大地水准面模型,对GPS测得的大地高程进行改算,可得到较高精度的正常高成果.方法应用于青海三江流域1:20万区域重力调查工作中,取得了较好的效果.  相似文献   

我国现代高程测定关键技术若干问题的研究及进展   总被引：5，自引：0，他引：5  

李建成 《武汉大学学报(信息科学版)》2007,32(11):980-987

阐述了大地水准面在大地测量学及相关地球科学中的科学意义、作用及其应用,提出了利用GPS技术结合高精度似大地水准面代替我国高程测定的思路,分析了目前地球重力场长波、中波和短波在计算cm级大地水准面中具备的条件,论述了确定1 cm精度城市和5 cm省级似大地水准面的若干关键技术问题及其必要性和可行性,提出了我国cm级大地水准面确定中需解决的主要理论问题和若干关键技术,评述了我国局部大地水准面的主要进展和取得的成果。  相似文献   

Detection of Local Geoid Deformations by Gravity Disturbances from GPS/Gravimetric Observations     

A. Martín  A.B. Anquela  J. Padín  J.L. Berné 《Studia Geophysica et Geodaetica》2005,49(1):43-62

This paper deals with a method for detection of local geoid deformations; as a consequence, the methods main application concerns geoid adjustment to GPS/levelling points. This is based on the fact that these points should present no local geoid deformation to avoid errors in the adjustments. These type of miscalculations would lead to an incorrect adjustment and result in further errors in subsequent studies with GPS in the proximity at the point with local deformation.The method proposed is based on predictions of gravity disturbance from geoid undulations using Poisson integral with modified kernel, and its comparison with the gravity disturbance from GPS and gravimetric observations.The use of gravity disturbance instead of gravity anomalies has been chosen since gravity disturbance is a quantity derived from GPS and not from levelling. The loss of accuracy arising with a local height reference system is therefore theoretically avoided as far as the differences in geodetic reference systems regarding positions of gravity measurements and coefficients of the global models are accounted for.Extended numerical tests using computed geoidal undulations and the corresponding gravity disturbances obtained from the geopotential model GPM98cr computed up to degree 720 illustrate the validity of the proposed method and its usefulness as local geoid deformations detection tool.Finally, the method is tested using real GPS/Gravimetric data and geoid models IBERGEO95 and EGG97 with good results.  相似文献   

A Local Least-Squares Modification of Stokes’ Formula     

L.E. Sjöberg 《Studia Geophysica et Geodaetica》2005,49(1):23-30

The combination of Stokes formula and an Earth Gravity Model (EGM) for geoid determination has become a standard procedure. However, the way of modifying Stokes formula vary from author to author, and numerous methods of modification exist. Most methods are deterministic, with the primary goal of reducing the truncation bias committed by limiting the area of Stokes integration around the computation point, but there are also some stochastic methods with the explicit goal to reduce the global mean square error of the geoid height estimator stemming from the truncation bias as well as the random errors of the EGM and the gravity data. The latter estimators are thus, at least from a theoretical point of view, optimal in a global mean sense, but in a local sense they may be far from optimality.Here we take advantage of the error variance-covariance matrices of the EGM and the terrestrial gravity data to derive the modification parameters of Stokes kernel in a local least-squares sense. The solution is given for the unbiased type of modification of Stokes formula of Sjöberg (1991).  相似文献   

Spherical harmonic representation of the gravitational potential of discrete spherical mass elements   总被引：1，自引：0，他引：1  

Stephen T. Sutton  Henry N. Pollack  Michael J. Jackson 《Geophysical Journal International》1991,107(1):77-82

b
We present expressions in a spherical harmonic framework for the gravitational potential of discrete point, surface, and volume mass elements located at any depth within a sphere. Through analysis of the spherical harmonic spectrum, insight is gained into the properties of the potentials arising from a variety of mass distributions. A point mass at the surface of a sphere displays the richest harmonic spectrum in all degrees; spectra become increasingly reddened as the source mass is distributed through larger elements of area or volume, or is located at greater depths below the surface of the reference sphere. The spectra of dipolar distributions, useful in representing compensated masses, are depressed, especially in the low harmonic degrees, relative to the spectra of monopole elements.  相似文献   

On the distribution of anomalous mass within the Earth: forward models of the gravitational potential spectrum using ensembles of discrete mass elements   总被引：1，自引：0，他引：1  

Michael J. Jackson  Henry N. Pollack  Stephen T. Sutton 《Geophysical Journal International》1991,107(1):83-94

b
We investigate forward models of the gravitational potential spectrum generated by ensembles of discrete sources of anomalous mass, having radial distributions with different statistical properties. Models with a random distribution of point source locations throughout the volume of the mantle produce spectra similar to that of the Earth only when the (absolute) source magnitudes increase strongly with depth, at least as d ^1.5. The effects of the geographic (latitude-longitude) distribution of source locations are generally unimportant in determining the general degree dependence of the potential spectrum. The dimensions of the sources are also of secondary importance, at least up to an angular diameter of about 40, i.e., continent-sized. Sources of this size confined to the upper mantle do not appear capable of producing the degree dependence of the observed geopotential spectrum; the low harmonics (2-4) in particular appear to require lower mantle sources of considerable strength. Further, at least some of these deep sources must be largely monopolar in nature, (i.e., uncompensated) due to the stronger depth attenuation of dipole (compensated) sources. Because topography on the core-mantle boundary must be either isostatically or dynamically compensated, it may contribute little strength to the observed potential spectrum.  相似文献